(AP) – Data from the National Oceanic and Atmospheric Administration confirms 84 percent of United States cities now experience at least an additional week of warmer-than-normal spring days than they did in the 1970s. That’s good news for some warm weather crops, not so great for cool weather crops and areas dependent on snow-fed water. It also significantly impacts what kinds of produce farmers markets provide and when.

Across the globe, climate change is affecting water levels, insect populations and migration patterns, as well as growing conditions. Researchers with the International Food Policy Research Institute project suitable croplands for corn, potatoes, rice and wheat will shift radically within the next 25 years; in some cases, farmers will be forced to plant new crops. Closer to home, the effects are being felt in grocery stores and farmers markets. As seasons shift, farmers bring different foods to market, while grocers use industrial methods to extend seasonality.

A new Climate Central analysis finds human-caused climate change drives warmer springs in 98 percent of 241 major U.S. cities. 

The value of the farmers market to the consumer comes in the freshness and reliability. 

“Put simply, you can taste the difference,” explains Bethany Harris, farm purveyor for Gjelina Group.

Paula Hamilton, of Hamilton Farms Mushrooms in Corydon, Ind., adds, “Farmers markets offer a place that removes the barriers between the producers of good, whole foods and the people who want them. It’s a match made in heaven.”

While a casual farmers market shopper may not spot the differences, seasoned regulars have noticed a shift over the years. 

“The seasons have changed rather significantly year to year. Peas and apricots are great examples of things we either see or don’t based on an early or late start to spring. We saw no peas two years ago, but a decent crop last year. We also saw them twice, as Nichols Farm was able to harvest snap peas from the cover crop in late fall. I have never seen that before,” points out Chef Devon Quinn, partner of Eden, a contemporary farm-to-table restaurant in Chicago’s Avondale neighborhood. “Some crops shifted as many as four weeks with a warmer-than-usual spring.”

Austin Jones, owner of Blooming Hill Farm, said, “I really think a lot depends on what the weather is like in a given year. For example, people want peas and ramps in the springtime, but if it’s a cold year, sometimes these aren’t available in April, you have to wait until May – and even then, peas could be longer if we don’t start them in the greenhouse. Sometimes we don’t have snap peas available in the field until June.

“I feel like there is a general disconnect there between the everyday consumer and what is actually available seasonally and locally because these ‘hyper seasonal’ items are often available from commercial distributors much earlier than they are from local producers.”

Added Quinn, “Farms are seeing new insects invade their fields that they have not seen in the past – beetles, grasshoppers and scale. This has been devastating for some farms. Flatwater Farms in Michigan was my primary supply of Esmee arugula two years ago, but it was hardly able to produce any last year. They were devastated by beetles. My wife and I visited Werp Farm in Buckley, Mich., last summer, and Tina pointed out grasshoppers that had never been seen there previously.”

Local restaurants that depend on farmers markets for their menu planning and providing fresh produce to their customers are also impacted by the changes. Certain vegetable dishes may not make it on the menu. Chefs adjust their ingredients, or even eliminate or delay offerings to diners to accommodate what isn’t available. Communication is key.

“At any given time, a farmer’s produce list gives you an accurate snapshot of the season and helps us convey that message to the diner,” says Eric Leveillee, executive chef at The Rittenhouse Hotel in Philadelphia, Pa. “It’s also nice to be able to communicate directly with the farmers about our wants and needs, as well as guests’ wants and needs, and having an open dialogue when the product is really great or not so great ensures we can always deliver the highest quality ingredients.”

Harris said, “Staying in constant dialogue allows us to keep a pulse on what is happening across the state and plan when and how to adjust to the ebb and flow of availability. For example, when a farm in Los Olivos is gapping on lettuce, we can adjust accordingly and keep my favorite Market Greens salad on the menu year-round.”

Executive Chef Kali Kopley, co-owner of Pico Los Alamos, said, “Seasonality steers my boat. Especially if I know the farmer is very excited about a certain product, and there is enough to add a new exciting dish to my menu. For me, there’s nothing worse than being at a restaurant that has a fresh product on the menu that is not in season. This tells me right away that they have large trucks pulling up and delivering food from a large food chain.”